<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script>
			var a=prompt("input a number:");
			//123aaa
			if(isNaN(a)){
				alert("无法转换成数字");
			}else{
				var i=parseInt(a); 
				alert(i);
				alert(i+5);
			}
			
		</script>
	</head>
	<body>
	</body>
</html>
